Crystalline compound as semicarbazide-sensitive amine oxidase (ssao) enzyme inhibitor

ABSTRACT

A specific crystalline mesylate salt form of (3S)-Tetrahydrofuran-3-yl (4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate, and the use of the same in medicine. (Formula (I))

FIELD OF THE INVENTION

This invention relates to the crystalline mesylate salt form of(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate,to methods of production and isolation, to pharmaceutical compositionswhich include this compound and a pharmaceutically acceptable carrier,and to pharmaceutical methods of treatment.

BACKGROUND OF THE INVENTION

Semicarbazide-sensitive amine oxidase (SSAO) activity is an enzymeactivity expressed by Vascular Adhesion Protein-1 (VAP-1) or AmineOxidase, Copper Containing 3 (AOC3), belongs to the copper-containingamine oxidase family of enzymes (EC.1.4.3.6). Therefore inhibitors ofthe SSAO enzyme may also modulate the biological functions of the VAP-1protein.

SSAO activity has been found in a variety of tissues including vascularand non-vascular smooth muscle tissue, endothelium, and adipose tissue[Lewinsohn, Braz. J. Med. Biol. Res. 1984, 17, 223-256; Nakos & Gossrau,Folia Histochem. Cytobiol. 1994, 32, 3-10; Yu et al., Biochem.Pharmacol. 1994, 47, 1055-1059; Castillo et al., Neurochem. Int 1998,33, 415-423; Lyles & Pino, J. Neural. Transm. Suppl. 1998, 52, 239-250;Jaakkola et al., Am. J. Pathol. 1999, 155, 1953-1965; Morin et al., J.Pharmacol. Exp. Ther. 2001, 297, 563-572; Salmi & Jalkanen, TrendsImmunol. 2001, 22, 211-216]. In addition, SSAO protein is found in bloodplasma and this soluble form appears to have similar properties as thetissue-bound form [Yu et al., Biochem. Pharmacol. 1994, 47, 1055-1059;Kurkijärvi et al., J. Immunol. 1998, 161, 1549-1557].

The precise physiological role of this abundant enzyme has yet to befully determined, but it appears that SSAO and its reaction products mayhave several functions in cell signalling and regulation. For example,recent findings suggest that SSAO plays a role in both GLUT4-mediatedglucose uptake [Enrique-Tarancon et al., J. Biol. Chem. 1998, 273,8025-8032; Morin et al., J. Pharmacol. Exp. Ther. 2001, 297, 563-572]and adipocyte differentiation [Fontana et al., Biochem. J. 2001, 356,769-777; Mercier et al., Biochem. J. 2001, 358, 335-342]. In addition,SSAO has been shown to be involved in inflammatory processes where itacts as an adhesion protein for leukocytes [Salmi & Jalkanen, TrendsImmunol. 2001, 22, 211-216; Salmi & Jalkanen, in “Adhesion Molecules:Functions and Inhibition” K. Ley (Ed.), 2007, pp. 237-251], and mightalso play a role in connective tissue matrix development and maintenance[Langford et al., Cardiovasc. Toxicol. 2002, 2(2), 141-150; Göktürk etal., Am. J. Pathol. 2003, 163(5), 1921-1928]. Moreover, a link betweenSSAO and angiogenesis has recently been discovered [Noda et al., FASEBJ. 2008, 22(8), 2928-2935], and based on this link it is expected thatinhibitors of SSAO have an anti-angiogenic effect.

Several studies in humans have demonstrated that SSAO activity in bloodplasma is elevated in conditions such as congestive heart failure,diabetes mellitus, Alzheimer's disease, and inflammation [Lewinsohn,Braz. J. Med. Biol. Res. 1984, 17, 223-256; Boomsma et al., Cardiovasc.Res. 1997, 33, 387-391; Ekblom, Pharmacol. Res. 1998, 37, 87-92;Kurkijärvi et al., J. Immunol. 1998, 161, 1549-1557; Boomsma et al.,Diabetologia 1999, 42, 233-237; Meszaros et al., Eur. J. Drug Metab.Pharmacokinet. 1999, 24, 299-302; Yu et al., Biochim. Biophys. Acta2003, 1647(1-2), 193-199; Mátyus et al., Curr. Med. Chem. 2004, 11(10),1285-1298; O'Sullivan et al., Neurotoxicology 2004, 25(1-2), 303-315;del Mar Hernandez et al., Neurosci. Lett. 2005, 384(1-2), 183-187]. Ithas been suggested that reactive aldehydes and hydrogen peroxideproduced by endogenous amine oxidases contribute to the progression ofcardiovascular diseases, diabetic complications and Alzheimer's disease[Callingham et al., Prog. Brain Res. 1995, 106, 305-321; Ekblom,Pharmacol. Res. 1998, 37, 87-92; Yu et al., Biochim. Biophys. Acta 2003,1647(1-2), 193-199; Jiang et al., Neuropathol Appl Neurobiol. 2008,34(2), 194-204]. Furthermore, the enzymatic activity of SSAO is involvedin the leukocyte extravasation process at sites of inflammation whereSSAO has been shown to be strongly expressed on the vascular endothelium[Salmi et al., Immunity 2001, 14(3), 265-276; Salmi & Jalkanen, in“Adhesion Molecules: Functions and Inhibition” K. Ley (Ed.), 2007, pp.237-251]. Accordingly, inhibition of SSAO has been suggested to have atherapeutic value in the prevention of diabetic complications and ininflammatory diseases [Ekblom, Pharmacol. Res. 1998, 37, 87-92; Salmi etal., Immunity 2001, 14(3), 265-276; Salter-Cid et al., J. Pharmacol.Exp. Ther. 2005, 315(2), 553-562].

WO2007/146188 teaches that blocking SSAO activity inhibits leucocyterecruitment, reduces the inflammatory response, and is expected to bebeneficial in prevention and treatment of seizures, for example, inepilepsy.

O'Rourke et al (J Neural Transm. 2007; 114(6):845-9) examined thepotential of SSAO inhibitors in neurological diseases, having previouslydemonstrated the efficacy of SSAO inhibition in a rat model of stroke.An SSAO inhibitor is tested on relapsing-remitting experimentalautoimmune encephalomyelitis (EAE), a mouse model that shares manycharacteristics with human multiple sclerosis. The data demonstrates thepotential clinical benefit of small molecule anti-SSAO therapy in thismodel and therefore in treatment of human multiple sclerosis.

SSAO knockout animals are phenotypically overtly normal but exhibit amarked decrease in the inflammatory responses evoked in response tovarious inflammatory stimuli [Stolen et al., Immunity 2005, 22(1),105-115]. In addition, antagonism of its function in wild type animalsin multiple animal models of human disease (e.g. carrageenan-induced pawinflammation, oxazolone-induced colitis, lipopolysaccharide-induced lunginflammation, collagen-induced arthritis, endotoxin-induced uveitis) bythe use of antibodies and/or small molecules has been shown to beprotective in decreasing the leukocyte infiltration, reducing theseverity of the disease phenotype and reducing levels of inflammatorycytokines and chemokines [Kirton et al., Eur. J. Immunol. 2005, 35(11),3119-3130; Salter-Cid et al., J. Pharmacol. Exp. Ther. 2005, 315(2),553-562; McDonald et al., Annual Reports in Medicinal Chemistry 2007,42, 229-243; Salmi & Jalkanen, in “Adhesion Molecules: Functions andInhibition” K. Ley (Ed.), 2007, pp. 237-251; Noda et al., FASEB J. 200822(4), 1094-1103; Noda et al., FASEB J. 2008, 22(8), 2928-2935]. Thisanti-inflammatory protection seems to be afforded across a wide range ofinflammatory models all with independent causative mechanisms, ratherthan being restricted to one particular disease or disease model. Thiswould suggest that SSAO may be a key nodal point for the regulation ofthe inflammatory response, and it is therefore likely that SSAOinhibitors will be effective anti-inflammatory drugs in a wide range ofhuman and animal diseases. VAP-1 has also been implicated in theprogression and maintenance of fibrotic diseases including those of theliver and lung. Weston and Adams (J Neural Transm. 2011, 118(7),1055-64) have summarised the experimental data implicating VAP-1 inliver fibrosis, and Weston et al (EASL Poster 2010) reported thatblockade of VAP-1 accelerated the resolution of carbon tetrachlorideinduced fibrosis. In addition VAP-1 has been implicated in inflammationof the lung (e.g. Singh et al., 2003, Virchows Arch 442:491-495)suggesting that VAP-1 blockers would reduce lung inflammation and thusbe of benefit to the treatment of cystic fibrosis by treating both thepro-fibrotic and pro-inflammatory aspects of the disease.

SSAO (VAP-1) is up regulated in gastric cancer and has been identifiedin the tumour vasculature of human melanoma, hepatoma and head and necktumours (Yoong K F, McNab G, Hubscher S G, Adams D H. (1998), J Immunol160, 3978-88; Irjala H, Salmi M, Alanen K, Gre´nman R, Jalkanen S(2001), Immunol. 166, 6937-6943; Forster-Horvath C, Dome B, Paku S, etal. (2004), Melanoma Res. 14, 135-40.). One report (Marttila-lchihara F,Castermans K, Auvinen K, Oude Egbrink M G, Jalkanen S, Griffioen A W,Salmi M. (2010), J Immunol. 184, 3164-3173.) has shown that mice bearingenzymically inactive VAP-1 grow melanomas more slowly, and have reducedtumour blood vessel number and diameter. The reduced growth of thesetumours was also reflected in the reduced (by 60-70%) infiltration ofmyeloid suppressor cells. Encouragingly VAP-1 deficiency had no effecton vessel or lymph formation in normal tissue.

For the above reasons, it is expected that inhibition of SSAO willreduce the levels of pro-inflammatory enzyme products (aldehydes,hydrogen peroxide and ammonia) whilst also decreasing the adhesivecapacity of immune cells and correspondingly their activation and finalextra-vasation. Diseases where such an activity is expected to betherapeutically beneficial include all diseases where immune cells playa prominent role in the initiation, maintenance or resolution of thepathology, such inflammatory diseases and immune/autoimmune diseases.Examples of such diseases include multiple sclerosis, arthritis andvasculitis.

An unmet medical need exists for new and improved inhibitors of SSAO.WO2010/031789 (the content of which is herein incorporated by reference)discloses a promising class of SSAO inhibitor compounds, especiallypromising is Example 16, which is the free base of(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate,and has the following structure:

The free base of (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylateis an hygroscopic amorphous glass/gum. There is a need to produce(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatein a pure and crystalline form to enable formulations to meet exactingpharmaceutical requirements and specifications. It is desirable that theactive ingredient is produced in a form which is amenable to large-scaleproduction. It is desirable that the product is in a form that isreadily filterable and easily dried. It is desirable also that theproduct is stable for extended periods of time without the need forspecialised storage conditions.

SUMMARY OF THE INVENTION

The applicant has discovered a crystalline form of the mesylate salt of(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]-pyridine-5-carboxylatehaving surprisingly improved properties over the known free base. Theimproved properties include high thermal stability, ease of filtration,ease of drying, and reduced hygroscopicity.

The mesylate salt (i.e the methanesulphonic acid salt) of(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylateis shown to be highly crystalline by X-ray powder diffraction (XRPD) andpolarised light microscopy (PLM). The improved thermal stability isdemonstrated by the high melting point of 189° C. The reducedhygroscopicity is demonstrated by the stability of the crystalline saltfor up to three days storage at a temperature of 40° C. in anenvironment having a relative humidity of 75%. The present inventionincludes a composition comprising the crystalline mesylate salt of(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]-pyridine-5-carboxylate,and one or more pharmaceutically acceptable excipients.

The crystalline mesylate salt of (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylateis expected to be useful in the treatment of inflammation, aninflammatory disease, an immune or an autoimmune disorder, or inhibitionof tumour growth. In an embodiment the the inflammation or inflammatorydisease or immune or autoimmune disorder is arthritis (includingrheumatoid arthritis, juvenile rheumatoid arthritis, osteoarthritis andpsoriatic arthritis), synovitis, vasculitis, Sjogren's disease, acondition associated with inflammation of the bowel (including Crohn'sdisease, ulcerative colitis, inflammatory bowel disease and irritablebowel syndrome), atherosclerosis, multiple sclerosis, Alzheimer'sdisease, vascular dementia, Parkinson's disease, cerebral amyloidangiopathy, cerebral autosomal dominant arteriopathy with subcorticalinfarcts and leukoencephalopathy, a pulmonary inflammatory disease(including asthma, chronic obstructive pulmonary disease and acuterespiratory distress syndrome), a fibrotic disease (including idiopathicpulmonary fibrosis, cardiac fibrosis, liver fibrosis and systemicsclerosis (scleroderma)), an inflammatory disease of the skin (includingcontact dermatitis, atopic dermatitis and psoriasis), an inflammatorydisease of the eye (including age related macular degeneration, uveitisand diabetic retinopathy), systemic inflammatory response syndrome,sepsis, an inflammatory and/or autoimmune condition of the liver(including autoimmune hepatitis, primary biliary cirrhosis, alcoholicliver disease, sclerosing cholangitis, and autoimmune cholangitis),diabetes (type I or II) and/or the complications thereof, chronic heartfailure, congestive heart failure, an ischemic disease (including strokeand ischemia-reperfusion injury) or myocardial infarction and/or thecomplications thereof, or epilepsy.

The present invention includes the use of the crystalline mesylate saltof (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]-pyridine-5-carboxylatein the manufacture of a medicament for the treatment or prevention ofthe above-mentioned conditions and diseases. The invention also includesmethods for treatment or prevention of such conditions and diseases,comprising administering to a mammal, including man, in need of suchtreatment an effective amount of a compound as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the XRPD of (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatefree base.

FIG. 2 shows the XRPD of crystalline of (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate salt. The XRPD is run in duplicate.

DETAILED DESCRIPTION OF THE INVENTION Definitions

“Treatment” as used herein includes prophylaxis of the named disorder orcondition, or amelioration or elimination of the disorder once it hasbeen established.

“An effective amount” refers to an amount of a compound that confers atherapeutic effect on the treated subject. The therapeutic effect may beobjective (i.e., measurable by some test or marker) or subjective (i.e.,subject gives an indication of or feels an effect).

“Pharmaceutically acceptable” means being useful in preparing apharmaceutical composition that is generally safe, non-toxic and neitherbiologically nor otherwise undesirable and includes being useful forveterinary use as well as human pharmaceutical use.

Unless stated to the contrary, the term “(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate”as used in connection with the crystalline salt form described hereinincludes a mixture of the (3S,4S) and (3R,4R) enantiomers. In anembodiment (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate,and salts thereof, has an absolute purity of >95%, preferably >99%, morepreferably >99.5%. In an embodiment (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemeans the (3S,4S) enantiomer having an enantiomeric purity of >95%,preferably >99%, more preferably >99.5%. In an embodiment(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatehas a diastereoisomeric purity of >95%, preferably >99%, more preferably>99.5%.

Compositions

For clinical use, the crystalline compound of the invention isformulated into pharmaceutical formulations for various modes ofadministration. It will be appreciated that the compound of theinvention may be administered together with a physiologically acceptablecarrier, excipient, or diluent. The pharmaceutical compositions of theinvention may be administered by any suitable route, preferably by oral,rectal, nasal, topical (including buccal and sublingual), sublingual,transdermal, intrathecal, transmucosal or parenteral (includingsubcutaneous, intramuscular, intravenous and intradermal)administration.

Other formulations may conveniently be presented in unit dosage form,e.g., tablets and sustained release capsules, and in liposomes, and maybe prepared by any methods well known in the art of pharmacy.Pharmaceutical formulations are usually prepared by mixing the activesubstance, or a pharmaceutically acceptable salt thereof, withconventional pharmaceutically acceptable carriers, diluents orexcipients. Examples of excipients are water, gelatin, gum arabicum,lactose, microcrystalline cellulose, starch, sodium starch glycolate,calcium hydrogen phosphate, magnesium stearate, talcum, colloidalsilicon dioxide, and the like. Such formulations may also contain otherpharmacologically active agents, and conventional additives, such asstabilizers, wetting agents, emulsifiers, flavouring agents, buffers,and the like. Usually, the amount of active compounds is between 0.1-95%by weight of the preparation, preferably between 0.2-20% by weight inpreparations for parenteral use and more preferably between 1-50% byweight in preparations for oral administration.

The formulations can be further prepared by known methods such asgranulation, compression, microencapsulation, spray coating, etc. Theformulations may be prepared by conventional methods in the dosage formof tablets, capsules, granules, powders, syrups, suspensions,suppositories or injections. Liquid formulations may be prepared bydissolving or suspending the active substance in water or other suitablevehicles. Tablets and granules may be coated in a conventional manner.To maintain therapeutically effective plasma concentrations for extendedperiods of time, the compound of the invention may be incorporated intoslow release formulations.

The dose level and frequency of dosage of the specific compound willvary depending on a variety of factors including the potency of thespecific compound employed, the metabolic stability and length of actionof that compound, the patient's age, body weight, general health, sex,diet, mode and time of administration, rate of excretion, drugcombination, the severity of the condition to be treated, and thepatient undergoing therapy. The daily dosage may, for example, rangefrom about 0.001 mg to about 100 mg per kilo of body weight,administered singly or multiply in doses, e.g. from about 0.01 mg toabout 25 mg each. A typical total daily dosage for a human is 1 to 2000mg/day, preferably from 200 to 2000 mg/day, more preferably from 500 to2000 mg/day. Normally, such a dosage is given orally but parenteraladministration may also be chosen.

Experimental Methods Analytical Methods X-Ray Powder Diffraction (XRPD)

X-Ray Powder Diffraction patterns were collected on a Bruker AXS C2GADDS diffractometer using Cu Kα radiation (40 kV, 40 mA), automated XYZstage, laser video microscope for auto-sample positioning and a HiStar2-dimensional area detector. X-ray optics consisted of a single GObelmultilayer mirror coupled with a pinhole collimator of 0.3 mm. A weeklyperformance check is carried out using a certified standard NIST 1976Corundum (flat plate). The beam divergence, i.e. the effective size ofthe X-ray beam on the sample, was approximately 4 mm. A θ-θ continuousscan mode was employed with a sample to detector distance of 20 cm whichgives an effective 2θ range of 3.2°-29.7°. Typically the sample would beexposed to the X-ray beam for 120 seconds. The software used for datacollection was GADDS for WNT 4.1.16 and the data were analysed andpresented using Diffrac Plus EVA v 9.0.0.2 or v 13.0.0.2. Samples rununder ambient conditions were prepared as flat plate specimens usingpowder as received without grinding. Approximately 1-2 mg of the samplewas lightly pressed on a glass slide to obtain a flat surface. Samplesrun under non-ambient conditions were mounted on a silicon wafer withheat conducting compound. The sample was then heated to the appropriatetemperature at ca 10° C./min and subsequently held isothermally for ca 1min before data collection was initiated.

Alternatively, X-Ray Powder Diffraction patterns were collected on aBruker D8 diffractometer using Cu Kα radiation (40 kV, 40 mA), θ-2θgoniometer, and divergence of V4 and receiving slits, a Ge monochromatorand a Lynxeye detector. The instrument is performance checked using acertified Corundum standard (NIST 1976). The software used for datacollection was Diffrac Plus XRD Commander v2.5.0 and the data wereanalysed and presented using Diffrac Plus EVA v 11.0.0.2 or v 13.0.0.2.Samples were run under ambient conditions as flat plate specimens usingpowder as received. Approximately 20 mg of the sample was gently packedinto a cavity cut into polished, zerobackground (510) silicon wafer. Thesample was rotated in its own plane during analysis. The details of thedata collection are—angular range: 2 to 42° 2θ; step size: 0.05° 2θ;collection time: 0.5 s/step.

Nuclear Magnetic Resonance (NMR)

¹H NMR spectra were collected on a Bruker 400 MHz instrument equippedwith an auto sampler and controlled by a DRX400 console. Automatedexperiments were acquired using ICONNMR v4.0.4 (build 1) running withTopspin v 1.3 (patch level 10) using the standard Bruker loadedexperiments. For non-routine spectroscopy, data were acquired throughthe use of Topspin alone. Samples were prepared in d6-DMSO, unlessotherwise stated. Off-line analysis was carried out using ACDSpecManager v 12.00 (build 29094). Alternatively, ¹H NMR spectra werecollected on a Bruker Avance III 400 MHz QNP Ultrashield Plus Cryo.

Liquid Chromatography-Mass Spectrometry (LCMS)

Analytical LCMS was performed on an Agilent 1100 HPLC system with aWaters ZQ mass spectrometer using a Phenomenex Synergi column (RP-Hydro,150×4.6 mm, 4 um, 1.5 mL/min, 30° C., gradient 5-100% MeCN (+0.085% TFA)in water (+0.1% TFA) over 7 min—held for 0.5 min, 200-300 nm).

Differential Scanning calorimetry (DSC)

DSC data were collected on a TA Instruments Q2000 equipped with a 50position autosampler. The calibration for thermal capacity was carriedout using sapphire and the calibration for energy and temperature wascarried out using certified indium. Typically 0.5-3 mg of each sample,in a pin-holed aluminium pan, was heated at 10° C./min from 25° C. to350° C. A purge of dry nitrogen at 50 mL/min was maintained over thesample. Modulated temperature DSC was carried out using an underlyingheating rate of 2° C./min and temperature modulation parameters of±1.27° C./min and 60 seconds. The instrument control software wasAdvantage for Q Series v2.8.0.392 and Thermal Advantage v4.8.3 and thedata were analysed using Universal Analysis v4.3A.

Thermo-Gravimetric Analysis (TGA)

TGA data were collected on a TA Instruments Q500 TGA, equipped with a 16position autosampler. The instrument was temperature calibrated usingcertified Alumel and Nickel. Typically 5-30 mg of each sample was loadedonto a pre-tared platinum crucible and aluminium DSC pan, and was heatedat 10° C./min from ambient temperature to 350° C. A nitrogen purge at 60mL/min was maintained over the sample. The instrument control softwarewas Advantage for Q Series v2.8.0.392 and Thermal Advantage v4.8.3

Polarised Light Microscopy (PLM)

Samples were studied on a Leica LM/DM polarised light microscope with adigital video camera for image capture. A small amount of each samplewas placed on a glass slide, mounted in immersion oil and covered with aglass slip, the individual particles being separated as well aspossible. The sample was viewed with appropriate magnification andpartially polarised light, coupled to a lambda false-colour filter.

Hot Stage Microscopy (HSM) [Melting Point]

Hot Stage Microscopy was carried out using a Leica LM/DM polarised lightmicroscope combined with a Mettler-Toledo MTFP82HT hot-stage and adigital video camera for image capture. A small amount of each samplewas placed onto a glass slide with individual particles separated aswell as possible. The sample was viewed with appropriate magnificationand partially polarised light, coupled to a lambda false-colour filter,whilst being heated from ambient temperature typically at 10-20° C./min.

Chemical Purity Determination by HPLC

Purity analysis was performed on an Agilent HP1100 series systemequipped with a diode array detector and using ChemStation softwarevB.02.01-SR1 using the method detailed below (Table 1).

TABLE 1 Sample Preparation 0.5 mg/ml in acetonitrile:water 1:1 ColumnSupelco Ascentis Express C18, 100 × 4.6 mm, 2.7 μm Column Temperature (°C.) 25 Injection (μl) 5 Wavelength, Bandwidth (nm) 255, 90 nm Flow Rate(ml · min⁻¹) 2.0 Phase A 0.1% TEA in water Phase B 0.085% TEA inacetonitrile Timetable: Time (min) % Phase A % Phase B 0 95 5 6 5 95 6.295 5 8 95 5

Chiral Purity Determination by Chiral HPLC

Chiral HPLC was performed on an Agilent 1200 system using an AstecChirobiotic T 100×4.6 mm 5 um column, polar reverse phase, 150×4.6 mm, 5um, isocratic 85% MeOH 15% 20 mM ammonium acetate over 10 min, 1.0mL/min, 220 nm.

Water Determination by Karl Fischer Titration (KF)

The water content of each sample was measured on a Mettler Toledo DL39Coulometer using Hydranal Coulomat AG reagent and an argon purge.Weighed solid samples were introduced into the vessel on a platinum TGApan which was connected to a subaseal to avoid water ingress. Approx 10mg of sample was used per titration and duplicate determinations weremade.

Gravimetric Vapour Sorption (GVS)

Sorption isotherms were obtained using a SMS DVS Intrinsic moisturesorption analyser, controlled by DVS Intrinsic Control softwarev1.0.0.30. The sample temperature was maintained at 25° C. by theinstrument controls. The humidity was controlled by mixing streams ofdry and wet nitrogen, with a total flow rate of 200 mL/min The relativehumidity was measured by a calibrated Rotronic probe (dynamic range of1.0-100% RH), located near the sample. The weight change, (massrelaxation) of the sample as a function of % RH was constantly monitoredby the microbalance (accuracy ±0.005 mg). Typically 5-20 mg of samplewas placed in a tared mesh stainless steel basket under ambientconditions. The sample was loaded and unloaded at 40% RH and 25° C.(typical room conditions). A moisture sorption isotherm was performed asoutlined below (2 scans giving 1 complete cycle). The standard isothermwas performed at 25° C. at 10% RH intervals over a 0.5-90% RH range.Data analysis was undertaken in Microsoft Excel using DVS Analysis Suitev6.0.0.7. Method parameters for SMS DVS intrinsic experiments:adsorption scan 1 40-90; desorption/adsorption scan 2 90-0, 0-40;intervals (% RH) 10; number of scans 4; flow rate (mL/min) 200;temperature (° C.) 25; stability (° C./min) 0.2; sorption time (h) 6 htime out. The sample was recovered after completion of the isotherm andre-analysed by XRPD.

Ion Chromatography (IC)

Data were collected on a Metrohm 761 Compact IC (for cations) and aMetrohm 861 Advanced Compact IC (for anions) using IC Net software v2.3.Accurately weighed samples were prepared as stock solutions in anappropriate dissolving solution and diluted 1:9 prior to testing.Quantification was achieved by comparison with standard solutions ofknown concentration of the ion being analysed. IC Method Parameters forAnion Chromatography: type of method—anion exchange; column—Metrosep ASupp 5-250 (4.0×250 mm); column temperature (° C.) ambient; injection(μl) 20; detection—conductivity detector; flow rate (mL/min) 0.7; eluent3.2 mM sodium carbonate, 1.0 mM sodium hydrogen carbonate in 5% aqueousacetone.

Results

Crystalline mesylate salt was isolated and characterised using some orall of XRPD, ¹H NMR, DSC, TGA, GVS, IC, PLM, HSM, HPLC and KF (see Table2).

Summary properties of (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylateFree Base and Crystalline Mesylate Salt

TABLE 2 Sample Form MP Hygroscopicity Free base Amorphous — Deliquescedat gum 25° C./60% RH in <24 h Crystalline Crystalline 189° C.Deliquesced at mesylate solid 40° C./75% RH after salt 3 days

Stability/Hygroscopicity During Long Term Storage

Crystalline (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate was also assessed for stability and hygroscopicity whendispensed in 3 g aliquots in double LDPE liners, sealed with cable tieand placed, with a desiccant pouch into a foil bag, which wassubsequently heat-sealed. The foil bag was then placed into an HDPE kegfitted with an HDPE lid. These conditions mirror typical GMP levelstorage conditions. Stability was assessed by HPLC and hygroscopicitywas assessed by Karl Fisher (KF) titration. Crystalline(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate degraded by only 0.1% with no water uptake over 3 years at 25°C./60% RH, and by only 0.1% with only 0.1% water uptake after 6 monthsat 40° C./75% RH.

Single Crystal X-Ray Diffraction (SXRPD)

Data were collected on an Oxford Diffraction Supernova Dual Source, Cuat zero, Atlas CCD diffractometer equipped with an Oxford CryosystemsCobra cooling device. The data was collected using CuKα radiation.Structures were typically solved using either SHELXS or SHELXD programsand refined with the SHELXL program as part of the Bruker AXS SHELXTLsuite. Unless otherwise stated, hydrogen atoms attached to carbon wereplaced geometrically and allowed to refine with a riding isotropicdisplacement parameter. Hydrogen atoms attached to a heteroatom werelocated in a difference Fourier synthesis and were allowed to refinefreely with an isotropic displacement factor.

Single Crystal Structure Determination

A single crystal of (3S)-tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate was grown by slow evaporation from ethyl acetate/methanol.

The structure solution was obtained by direct methods, full-matrixleast-squares refinement on F² with weighting w⁻¹=σ²(F_(o)²)+(0.0490P)²+(0.3000P), where P=(F_(o) ²+2Fc²)/3, anisotropicdisplacement parameters. Empirical absorption correction using sphericalharmonics, implemented in SCALE3 ABSPACK scaling algorithm.

Absolute structure parameter=0.002(13). Final wR²={Σ[w(F_(o)²−Fc²)²]/Σ[w(F_(o) ²)²]^(1/2)}=0.0657 for all data, conventionalR₁=0.024 on F values of 2651 reflections with F_(o)>4σ(F_(o)), S=1.007for all data and 234 parameters. Final Δ/σ(max) 0.000,

Δ/σ(mean), 0.000.

Final difference map between +0.24 and −0.288 e Å⁻³.

The solved crystal structure parameters were as follows (Table 3):

TABLE 3 Molecular C₁₅H₂₅N₃O₆S formula Molecular weight 375.44 Crystalsystem Orthorhombic Space group P2(1)2(1)2(1) a 8.75780(10)Å, α 90°, b9.70830(10)Å, β 90°, c 20.6736(2)Å, γ 90°, V 1757.74(3)Å³ Z 4 D_(c)1.419 g · cm⁻³ μ 1.975 mm⁻¹ Source, λ Cu-Kα, 1.5418Å F(000) 800 T100(2)K Crystal Colourless block, 0.09 × 0.05 × 0.02 mm Data truncatedto 0.80 Å θ_(max) 62.35° Completeness 99.2% Reflections 13291 Unique2736 reflections R_(int) 0.0256

The atomic co-ordinates were as follows:

TABLE 3 x y z S1 −0.953688 −0.131935 −0.071370 O1 −0.020659 −0.149398−0.484602 O2 −0.234768 −0.155566 −0.365860 O3 −0.474652 −0.066100−0.365092 O4 −0.912055 −0.134194 −0.140238 O5 −1.110792 −0.173740−0.060477 O6 −0.844708 −0.208722 −0.032208 N1 −0.412770 −0.253710−0.303870 N2 −0.617297 −0.224842 −0.147335 H2A −0.722228 −0.196131−0.146105 N3 −0.392648 −0.259773 −0.107928 H3A −0.324241 −0.261543−0.081273 C1 0.073273 −0.055487 −0.449929 H1A 0.096656 0.026304−0.476759 H1B 0.170449 −0.099983 −0.437205 C2 −0.017615 −0.014548−0.390676 H2B −0.004410 0.084643 −0.381074 H2C 0.014557 −0.068772−0.352479 C3 −0.183226 −0.046385 −0.408629 H3B −0.249376 0.037232−0.405075 C4 −0.171565 −0.096071 −0.477738 H4B −0.248192 −0.168773−0.486334 H4C −0.188739 −0.019057 −0.508271 C5 −0.383218 −0.150898−0.346637 C6 −0.560166 −0.254872 −0.270030 H6B −0.616936 −0.169106−0.281832 C7 −0.521333 −0.248342 −0.198878 C8 −0.536619 −0.232888−0.092882 H8A −0.575742 −0.221293 −0.050370 C9 −0.379700 −0.269963−0.174418 C10 −0.240769 −0.305362 −0.212417 H10A −0.184330 −0.381585−0.191434 H10B −0.172218 −0.224586 −0.215739 C11 −0.296381 −0.348962−0.279498 H11A −0.208892 −0.350915 −0.309809 H11B −0.339647 −0.443040−0.277151 C12 −0.659963 −0.380274 −0.288449 H12A −0.612652 −0.464685−0.269297 C13 −0.664766 −0.397753 −0.361667 H13A −0.560447 −0.406134−0.378360 H13B −0.714279 −0.317374 −0.381222 H13C −0.722663 −0.480993−0.372510 C14 −0.821261 −0.366359 −0.261740 H14A −0.816850 −0.355260−0.214661 H14B −0.880046 −0.449226 −0.272353 H14C −0.870697 −0.285637−0.281016 C15 −0.939731 0.041434 −0.046714 H15A −0.966523 0.048834−0.000821 H15C −1.009980 0.097844 −0.072401 H15B −0.834933 0.074003−0.053214

X-Ray Powder Diffraction

The powder X-ray diffraction pattern of the mesylate salt of(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatehad peaks at 8.549, 9.851, 10.899, 12.295, 13.198, 13.393, 14.083,15.897, 16.280, 17.097, 17.744, 18.289, 19.694, 20.180, 20.443, 20.597,20.886, 21.948, 22.112, 22.444, 23.194, 23.653, 24.144, 24.714, 25.292,25.590, 25.810, 26.526, 26.765, 27.084, 27.283, 27.662, 28.159, 28.996,29.135, 29.912 and 30.868 degrees 2θ. To take into account normalexperimental variation, the peaks identified above should be regarded ashaving an accuracy of up to +/−0.2 degrees 2θ, such as +/−0.1, +/−0.05,+/−0.01, +/−0.005, and +/−0.001. The relative intensities of these peakswere as follows (Table 4):

TABLE 4 Angle Intensity (2-Theta °) (%) 8.549 3.7 9.851 24.2 10.899 7.212.295 2.3 13.198 6.9 13.393 4.9 14.083 4.2 15.897 3.3 16.280 23.717.097 13.7 17.744 47.0 18.289 7.4 19.694 21.5 20.180 4.2 20.443 18.120.597 7.3 20.886 42.8 21.948 100.0 22.112 22.5 22.444 4.5 23.194 14.523.653 21.9 24.144 11.8 24.714 3.3 25.292 4.1 25.590 5.3 25.810 4.326.526 4.0 26.765 4.0 27.084 17.2 27.283 10.5 27.662 3.4 28.159 9.828.996 5.3 29.135 4.1 29.912 10.5 30.868 5.0

Synthesis

The following abbreviations have been used:

-   Aq Aqueous-   DCM Dichloromethane-   DI PEA Diisopropylethylamine-   ee Enantiomeric excess-   ES⁺ Electrospray-   EtOAc Ethyl acetate-   h Hour(s)-   HPLC High performance liquid chromatography-   HRMS High resolution mass spectrometry-   LCMS Liquid chromatography mass spectrometry-   M Molar-   MeOH Methanol-   [MH⁺] Protonated molecular ion-   min Minutes-   RP Reverse phase-   MS Mass spectrometry-   R_(T) Retention time-   sat Saturated-   THF Tetrahydrofuran-   TFA Trifluoroacetic acid

Experimental Methods

All reagents were commercial grade and were used as received withoutfurther purification, unless otherwise specified. Reagent grade solventswere used in all cases.

Analytical LCMS was performed on a Waters ZQ mass spectrometer connectedto an Agilent 1100 HPLC system. Analytical HPLC was performed on anAgilent 1100 system. High-resolution mass spectra (HRMS) were obtainedon an Agilent MSD-TOF connected to an Agilent 1100 HPLC system. Duringthe analyses the calibration was checked by two masses and automaticallycorrected when needed. Spectra are acquired in positive electrospraymode. The acquired mass range was m/z 100-1100. Profile detection of themass peaks was used. Flash chromatography was performed on either aCombiFlash Companion system equipped with RediSep silica columns or aFlash Master Personal system equipped with Strata SI-1 silica gigatubes.Reverse Phase HPLC was performed on a Gilson system (Gilson 322 pumpwith Gilson 321 equilibration pump and Gilson 215 autosampler) equippedwith Phenomenex Synergi Hydro RP 150×10 mm, YMC ODS-A 100/150×20 mm orChirobiotic T 250×10 mm columns. Reverse phase column chromatography wasperformed on a Gilson system (Gilson 321 pump and Gilson FC204 fractioncollector) equipped with Merck LiChroprep® RP-18 (40-63 μm) silicacolumns. The compounds were automatically named using ACD 6.0. Allcompounds were dried in a vacuum oven overnight.

Analytical HPLC and LCMS data were obtained with:

System A: Phenomenex Synergi Hydro RP (C18, 30×4.6 mm, 4 μm), gradient5-100% CH₃CN (+0.085% TFA) in water (+0.1% TFA), 1.5 mL/min, with agradient time of 1.75 min, 200 nm, 30° C.; or

System B: Phenomenex Synergi Hydro RP (C18, 150×4.6 mm, 4 μm), gradient5-100% CH₃CN (+0.085% TFA) in water (+0.1% TFA), 1.5 mL/min with agradient time of 7 min, 200 nm, 30° C.

Chiral HPLC data were obtained with:

System C: Chirobiotic V polar ionic mode (150×4.6 mm), 70% MeOH in 10 mMaq ammonium formate buffer, 1.0 mL/min, over 10 min, 200 nm, 30° C.

Intermediate 1 4-Isopropyl-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridinehydrochloride

Histamine dihydrochloride (61.9 g, 336 mmol) was dissolved in a solutionof NaOH (33.6 g, 841 mmol) in water (125 mL) and MeOH (500 mL), andisobutyraldehyde (61.4 mL, 672 mmol) was added. The reaction mixture washeated under reflux at 80° C. for 24 h, cooled to room temperature, thepH was adjusted to 7 with 1 M aq HCl solution (250 mL) and the solventswere removed in vacuo. The residue was dissolved in warm MeOH (300 mL),allowed to stand for 1 h, filtered and the solvents were removed invacuo. The residue was stirred in MeOH (50 mL) and acetone (400 mL) for2 h and was cooled to 4° C. for 2 h. The resulting precipitate wasfiltered and washed with acetone (100 mL) to give4-isopropyl-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine hydrochloride(33.0 g, 48.7%) as a white solid.

Analytical LCMS: purity >90% (System A, R_(T)=0.51 min), ES⁺: 166.4[MH]⁺.

Intermediate 2 4-Nitrophenyl4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate

Intermediate 1 (2.78 g, 8.28 mmol, 60% pure) and DIPEA (5.27 mL, 30.3mmol) were dissolved in DCM (100 mL). The reaction mixture was cooled to0° C. and 4-nitrophenyl chloroformate (4.07 g, 20.2 mmol) was added. Thereaction mixture was stirred at room temperature for 18 h. The reactionmixture was washed with sat aq NaHCO₃ solution (5×100 mL), dried (MgSO₄)and the solvents were removed in vacuo to give 4-nitrophenyl4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate(5.28 g, crude) as a yellow gum.

Analytical HPLC: purity 41% (System B, R_(T)=4.70 min); Analytical LCMS:purity 86% (System A, R_(T)=1.70 min), ES⁺: 331.0 [MH]⁺.

(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate

NaH (0.40 g, 10.0 mmol, 60% dispersion in mineral oil) was suspended inanhydrous THF (20 mL), cooled to 0° C. and (S)-3-hydroxytetrahydrofuran(0.88 g, 0.68 mL, 10.0 mmol) was added. The suspension was stirred at 0°C. for 30 min then added to a solution of Intermediate 2 (3.30 g, 10.0mmol, 70% pure) in THF (60 mL) and the reaction mixture was stirred atroom temperature. Two additional such portions of NaH and(S)-3-hydroxytetrahydrofuran in THF were added after 5 and 29 h,respectively. After 2 d the reaction mixture was quenched with water (10mL) and the solvents were removed in vacuo. The residue was dissolved inEtOAc (100 mL), washed with 1 M aq Na₂CO₃ solution (4×100 mL), dried(MgSO₄) and the solvents were removed in vacuo. The residue was purifiedby column chromatography (normal phase, 20 g, Strata SI-1, silicagigatube, DCM (200 mL) followed by 2%, 4% and 5% MeOH in DCM (200 mLeach)) and reverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min,gradient 30% to 60% (over 7 min) then 100% (3 min) MeOH in 10%MeOH/water) to give (3S)-tetrahydrofuran-3-yl4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate(34.8 mg, 1.1%) as a white solid.

Analytical HPLC: purity 100% (System B, R_(T)=3.63 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.01 min), ES⁺: 280.1 [MH]⁺.

(3S)-Tetrahydrofuran-3-yl-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate(39.91 mg) was dissolved in 10 mM ammonium formate buffer and MeOH (2mL, 1:1) and purified twice by reverse phase chiral HPLC (Chirobiotic T250×10 mm, 3 mL/min, isocratic run 70% MeOH in 10 mM ammonium formatebuffer (40 min), pH 7.4) to give a single diastereoisomer,(3S)-tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate(6.90 mg, 99% ee).

Analytical HPLC: purity 100% (System B, R_(T)=3.63 min); Chiral HPLC:purity 99.5% (System C, R_(T)=2.22 min); Analytical LCMS: purity 100%(System B, R_(T)=3.90 min), ES⁺: 280.1 [MH]⁺; HRMS calculated forC₁₄H₂₁N₃O₃: 279.1583, found 279.1571.

(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate,Methananesulfonic Acid Salt

(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]-pyridine-5-carboxylatefree base (460 mg, 1.65 mmol) was dissolved in EtOAc (10 mL) at roomtemperature to give a clear colourless solution. Methanesulphonic acid(107 uL) was added portion-wise with gentle heating. The solution wasallowed to cool to room temperature overnight. The resulting crystalswere collected by filtration, washed with EtOAc (2×10 mL) and driedovernight at 40° C. in vacuo. (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate salt was obtained with a 99% yield (615 mg) as a whitecrystalline solid. HPLC: Retention time 2.27 min, purity 99.5%. Meltingpoint: 189° C. LCMS: Retention time 4.19 min, ES⁺280.0 [MH]⁺, 100%purity. Chiral HPLC: Retention time 3.70 min, >99.5% de. ¹H NMR (400MHz, CDCl₃): δ_(H) 8.72 (1H, m, NHCHNH⁺), 5.29 (1H, m, OCH), 5.05 (0.5H,d, J 8.4 Hz, CCHN), 4.89 (0.5H, d, J 7.6 Hz, CCHN), 4.59 (0.5H, m, NCH_(A)CH_(B)), 4.39 (0.5H, m, NCH _(A)CH_(B)), 3.97-3.85 (4H, m, CH ₂OCH₂), 3.20 (1H, m, NCH_(A)CH _(B)), 2.89 (3H, s, CH ₃SO₃ ⁻), 2.89-2.72(2H, m, CCH ₂CH₂N), 2.23-2.07 (3H, m, CH(CH₃)₂, OCH₂CH ₂), 1.16 (3H, d,J 6.4 Hz, CH ₃) and 1.06-0.96 (3H, m, CH ₃).

1. Crystalline (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate salt having the space group P2(1)2(1)2(1), and unit celldimensions substantially as follows: a  8.75780(10)Å α 90° b 9.70830(10)Å, β 90°, c 20.6736(2)Å, γ 90°,


2. Crystalline (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate salt having an XRPD pattern containing the following 2θ valuemeasured using CuKα radiation: 21.948.
 3. The salt according to claim 2having an XRPD pattern containing the following 2θ values measured usingCuKα radiation: 17.744 and 21.948.
 4. The salt according to claim 2having an XRPD pattern containing the following 2θ values measured usingCuKα radiation: 17.744, 20.886, 21.948.
 5. The salt according to claim 2having an XRPD pattern containing the following 2θ values measured usingCuKα radiation: 17.744, 20.886, 21.948, and 9.851.
 6. The salt accordingto claim 2 having an XRPD pattern containing the following 2θ valuesmeasured using CuKα radiation: 17.744, 20.886, 21.948, 9.851 and 16.280.7. The salt according to claim 2 having an XRPD pattern containing thefollowing 2θ values measured using CuKα radiation: 9.851, 16.280,17.097, 17.744, 19.694, 20.443, 20.886, 21.948, 22.112, 23.194, 23.653,24.144, 27.084, 27.283 and 29.912.
 8. The salt according to claim 2having an XRPD pattern as set out in Table 4 and/or FIG.
 2. 9. A saltaccording to claim 1 having a purity of greater than 95%.
 10. A saltaccording to claim 1 having a purity of greater than 99%.
 11. A saltaccording to claim 1 having a purity of greater than 99.5%.
 12. A saltaccording to claim 1 having an enantiomeric purity of greater than 95%.13. A salt according to claim 1 having an enantiomeric purity of greaterthan 99%.
 14. A salt according to claim 1 having an enantiomeric purityof greater than 99.5%.
 15. A pharmaceutical composition comprising asalt according to claim 1, and one or more suitable excipients.
 16. Asalt according to claim 1 for use in the treatment of, or in themanufacture of a medicament for treatment of, inflammation, aninflammatory disease, an immune or an autoimmune disorder, or inhibitionof tumour growth.
 17. A method for the treatment of inflammation, aninflammatory disease, an immune or an autoimmune disorder, or inhibitionof tumour growth, which comprises administering to a subject sufferingsuch disease an effective amount of a salt as claimed in claim
 1. 18. Asalt according to claim 16 wherein the inflammation or inflammatorydisease or immune or autoimmune disorder is arthritis (includingrheumatoid arthritis, juvenile rheumatoid arthritis, osteoarthritis andpsoriatic arthritis), synovitis, vasculitis, Sjogren's disease, acondition associated with inflammation of the bowel (including Crohn'sdisease, ulcerative colitis, inflammatory bowel disease and irritablebowel syndrome), atherosclerosis, multiple sclerosis, Alzheimer'sdisease, vascular dementia, Parkinson's disease, cerebral amyloidangiopathy, cerebral autosomal dominant arteriopathy with subcorticalinfarcts and leukoencephalopathy, a pulmonary inflammatory disease(including asthma, chronic obstructive pulmonary disease and acuterespiratory distress syndrome), a fibrotic disease (including idiopathicpulmonary fibrosis, cardiac fibrosis, liver fibrosis and systemicsclerosis (scleroderma)), an inflammatory disease of the skin (includingcontact dermatitis, atopic dermatitis and psoriasis), an inflammatorydisease of the eye (including age related macular degeneration, uveitisand diabetic retinopathy), systemic inflammatory response syndrome,sepsis, an inflammatory and/or autoimmune condition of the liver(including autoimmune hepatitis, primary biliary cirrhosis, alcoholicliver disease, sclerosing cholangitis, and autoimmune cholangitis),diabetes (type I or II) and/or the complications thereof, chronic heartfailure, congestive heart failure, an ischemic disease (including strokeand ischemia-reperfusion injury) or myocardial infarction and/or thecomplications thereof, or epilepsy.
 19. A salt according to claim 16 fortreatment of a disease selected from rheumatoid arthritis,osteoarthritis, liver fibrosis, chronic obstructive pulmonary disease,multiple sclerosis, Sjogren's disease, Alzheimer's disease, Parkinson'sdisease, inflammatory bowel disease, or vascular dementia.
 20. A processof making crystalline (3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate salt by forming the mesylate salt from the free base of(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylate.21. A process according to claim 20 wherein the mesylate salt is formedby addition of methanesulphonic acid to the free base.
 22. Crystalline(3S)-Tetrahydrofuran-3-yl(4S)-4-isopropyl-1,4,6,7-tetrahydro-5H-imidazo[4,5-c]pyridine-5-carboxylatemesylate obtained by the process according to claim 20.